1. COMMUNICATION CONTROL
CHAPTER 12
COMMUNICATION
CONTROL

2. COMMUNICATION SUBSYSTEM EXPOSURE
Transmission impairments
Component Failure
Subversive Threats

3. Subversive threats to the Communication Subsystem
Release of message contents
Passive
Attacks
Traffic analysis
Message insertion
Message deletion
Message modification
Changed message order
Message duplication
Denial of message services
Spurious associations
Subversive
Threats
Active
attacks

4. PHYSICAL COMPONENT CONTROLS
Tramsmision Media
Twisted paier
Coaxial cable
Optical fiber
Bounded
Transimission
media
Terrestrial microware
Satellite microwave
Radio frequency
Infrared
Unbounded

5. Communication Lines
Modems
Port-Protection Devices
Multiplexors and Concentrators

6. LINE ERROR CONTROLS Error Detection Sends message Receiver Sender
Returns copy of message

7. Error Correction Forward error correcting codes
Retransmission of data in error(backward error correction)

8. FLOW CONTROLS
The simplest form of flow control is stop-and-wait flow control
The stop-and-wait flow control protocol is inefficient because the communication channel remains unused for periods of time while the receiver isprocessing the frames received.

9. TOPOLOGICAL CONTROLS Local Area Network Topologies Bus Topology
Tree Topology
Ring Topology
Star topology
Hybrid Topologies
Wide Area Network Topologies

10. CHANNEL ACCESS CONTROLS
Polling Methods
Contention Methods

11. CONTROLS OVER SUBVERSIVE THREATS
Link Encryption
End-to-End- Encryption
Stream Ciphers
Error Propagation Codes
Message authentication Codes
Message Sequence Numbers
Request-Response Mechanisms

12. INTERNETWORKING CONTROLS
Three types of devices are used to connect subnetworks in an internet :
Bridge
Router
Gateway

13. COMMUNICATION ARCHITECTURES AND CONTROLS
The architecture has seven layers of function.each of which has as sociated controls :
Physical - Session
Data link - Presentration
Network - App;ication
Transport

14. AUDIT TRAIL CONTROLS
Accounting Audit Trail
Operations Audit Trail

15. EXISTENCE CONTROLS
Some additional backup and recovery controls follow :
Where possible, place redundant components and spare parts throughout the network.
Use equipment with in-built fault diagnosis capabilities.
Acquire high-quality test equipment.
Ensure adequate maintenance of hardware and software, especially at remote site
Ensure that adequate logging facilities exist for recovery purposes, especially where store-and-forward operations must be carried out in the network.